Ariel Leader

The quirky 250cc two-stroke that broke the mould

Ariel Leader side view 

▲ Ariel Leaders are very stable on the move with
reasonable braking and good ergonomics. Two-up
will see your performance impaired, but you can
still get some touring down on one of these, with or without the little woman/man.

Ariel Leader

1961 Ariel Leader specifications
Ariel Leader features
The Ariel Leader engine
Suspension and brakes
Handling and fuel economy
Ariel Leader prices and production figures
Ariel Leader colours
Buying an Ariel Leader
Riding the Ariel Leader

1961 Ariel Leader specifications

Type: Air-cooled two-stroke parallel twin
Capacity: 247cc (250cc)
Bore & Stroke: 54mm x 54mm
BHP: 17.5 @ 6400rpm
Compression ratio: 10:1
Transmission: 4-speed, multi-plate clutch
Brakes: 6-inch single leading shoe
drums front and rear
Electrics: Lucas alternator, coil ignition, 6 volt
Front suspension: Trailing link fork
Rear suspension: Swinging arm,
twin shock absorbers/dampers
Wheels: 3.25 x 16-inch front & rear
Weight: 320lbs (dry)
Maximum speed: 70mph (approximately)


IN THE SUMMER OF 1958 the Ariel Leader made its first appearance on British roads. This quirky 249cc two-stroke twin was a result of Ariel’s brave and innovative (or is that foolish and ill-timed?) foray into the popular and growing lightweight-motorcycle/scooter market.

The design of the Leader was entrusted into the capable hands of Val Page and Bernard Knight. The designers set their aim high—combining all the best features of both scooter and motorcycle. Their progeny would be light, surefooted and easy to handle, but at the same time it would offer all the weather protection that scooter riders were accustomed to, and more.

And they both succeeded, and failed. The new bike birthed in the Ariel stables showed great promise, racing ahead to bag the Motorcycle News Best Bike of the Year award in 1959.

The Leader was modern and stylish and a breath of fresh air after the usual overweight models produced by the company at that time (Red Hunter, Square Four). But despite a very promising start, it was not the great commercial success it was hoped to be having missed its market by a fairly wide margin.



Ariel Leader features

The new model featured snazzy two-tone colour schemes and an elegant and effective Perspex windscreen wide enough to shield a rider’s hands from most of the elements and the wind-blast. The pressed-steel leg-shields came as standard. The drive chain and engine was enclosed in protective pressed-steel panels designed to keep the rider ‘oil-free’.

Extras included an eight-day clock, a chrome rear bumper, a rear parcel carrier and colour-coded panniers (equipped with a set of rear indicators).

To keep production costs to minimum, most of the Leader’s bodywork, along with the unusual welded box-beam that acted as a frame, was built from pressed-steel panels. If not exactly attractive, the frame was stiff and sturdy—an essential requirement for producing a well-behaved motorcycle. The rear section of the body hinged to allow access to the rear wheel.

The steel petrol tank (2 ½ gallon) was rubber mounted. It was placed in the frame under the seat leaving the dummy tank as a storage compartment large enough to house a small crash helmet.



The Ariel Leader engine

The 250cc two-stroke engine with its 180-degree crank hung from the frame on three pressed-steel brackets. To save weight, and presumably to cut production costs, the rear bracket doubled as an air-intake silencer chamber). The parallel twin cylinders were made of cast iron and angled forward at 45°. This move decreased the overall height of the engine which made it possible to be mounted in a low position, thus bringing the centre of gravity closer to the ground and improving stability.

The engine case which contained the crank, four-speed Burman CP gear box and inner side of the primary chain housing was cast as a single light-alloy shell. The cylinder head was also cast in light-alloy.

The engine proved to be reliable enough, provided that you kept your carburettor settings in check and didn’t starve the engine of lubricant. On the plus side, the engine could be dismantled without removing it from the frame.

A point to mention is that it's important to fit the Ariel Leader pistons the correct way around. Why? Because they have slightly offset gudgeon pins in Désaxé style. The Leader, however, isn't a true Désaxé engine in which the cylinders are offset in relation to the crank axis towards the direction of rotation thereby "biasing" the power stroke. In other words, a Désaxé engine, because its cylinders are offset, has the pistons either slightly ahead or slightly behind the crank centreline.

With the Leader, the cylinders are not offset. But the offset gudgeon pin has the same, or a similar, effect. Be warned when rebuilding.

The Leader was fitted with coil ignition and a Lucas alternator. The rest of the electrics were fairly standard fare, but (according to some riders, and disputed by others) with unreliable switches. A six-inch headlight just bordered on the right side of adequate. The contact breaker assembly was dodgy too.



Ariel Leader Suspension and brakes

The front suspension incorporated a trailing-link fork with two-way damping. The fork legs were encased in unconventional, golf-club shaped housings made from pressed-steel.

The 16-inch wire wheels delivered a surefooted ride giving the Leader a distinct advantage over its small-wheeled scooter counterparts. The wheels were supplied with whitewall tyres (still available) and quick-release, full-width hubs and drum brakes (6-inch x 1—1/8in). Both hubs and drums were originally manufactured from an aluminium alloy, but that changed by 1961 when both were made from cheaper, and heavier, cast iron—the change was said to be due to cracks developing in the original alloy fabrications.



Ariel Leader Handling and fuel economy

On a whole, the Ariel Leader was a success—in terms of fulfilling its brief and initial sales, anyway. The bike handled exceedingly well. The top speed of 70mph (on later models almost 80mph) was impressive. The engine ran efficiently and could return 70mpg at 60mph. It looked like the Leader would conquer the market. So much so, that in 1960 Ariel (under the control of BSA, note) discontinued production of their four-strokes, putting all their efforts to the Leader and its offshoot un-faired models: the Ariel Arrow and the Arrow Super Sports (colloquially referred to as the Golden Arrow).

It was a very bold and controversial corporate risk. But the times were changing, and old orthodoxies were crumbling. Cheap (ish) cars in the shape of the Austin Mini (1959) and the Ford Cortina (1962) were changing the shape of domestic transport in Britain. Something needed to be done to stop a diminishing market from imploding.

The Ariel Leader, on paper at least, looked as if it might throw the firm a lifeline and set a new biking (and for that matter, a new driving) trend. But despite the relative success of the model for the first few years of production, much of the public were confused and divided, and early hopes were soon dashed. Had the Leader been further developed in line with a four cylinder concept highlighting the possibilities of the design, the future might have been different (although the writing was clearly on the wall for the British motorcycle industry, and it was perhaps always a question of when, rather than if). But BSA, struggling to rationalise a monster company with too many arms and divisions, simply relinquished the Leader reigns and in 1965, the Ariel Leader and Ariel Arrow were discontinued.



Ariel Leader price and production figures

There were, however, a few practical criticisms. The relatively minor ones included shoddy paintwork and rough/heavy gear-change with an unfortunate tendency to slip into neutral when not wanted. And the centre stand could "ground out" when riding two up.

Another issue was that if you’d squinted at the engine and knew your European motorcycles, you couldn’t have missed the resemblance to the power unit used by German motorcycle firm, Adler. Just a coincidence? Certainly, Val Page and Bernard Knight were aware of a similar engine design by the German firm, Adler. But the differences are as great as the similarities, and the Leader should be viewed as an original concept rather than a copy.

But the biggest issue was the price. Although the Leader was designed with production economy in mind, the initial cost of tooling (etc) brought the final purchase price to £209 11s 7d. And this was decidedly more expensive then an average scooter, and only barely cheaper then a price of many “fully-grown” motorcycles.

Ariel built 18,347 Leaders, 9,789 Arrows, 6,217 Arrow Super Sports (Golden Arrow), and 844 of the smaller 200cc Arrows.

Sales, incidentally, were hampered by a lack of interest in export markets, not least the USA which was geared largely towards the leisure end of the market, as opposed to the commuter end. As a consequence, the comprehensive weather protection offered by the Leader was hardly a selling point.



Ariel Leader colours

Admiralty Grey was the original main colour for side panels, leg shields, front fork, and front mudguard, with either Cherokee Red or Oriental Blue above. Later bikes had a Dark Seal Grey option for the upper body. In 1964, Leaders were available in an Ivory/Flamboyant Red livery; Ivory/British Racing Green; Ivory/Aircraft Blue. Black was also optional, and we're advised that Red/Sky Blue was yet another colour choice.



Buying an Ariel Leader

Aside from a basic visual inspection—such as checking for crash damage, rust, and obvious missing parts—buyers should ensure that the engine mounts are in good condition. Repairs here will quite probably require a complete frame strip. So pay special attention.

Check too that the bike is an easy and regular starter. Poor starting could be due to carburettor issues (Amal 375, 7/8th inch choke) or ignition issues (6v coil/alternator), which are easily remedied. Or it could be due to blown crankcase seals—which are a little more complicated to sort out.

Bikes in regular use invariably fare better than bikes that spend most of their time idle in the garage, so ask intelligent questions about usage and history. And don't be deterred by a scruffy hack. These are often in good tune and reliable.

The bottom end of an Ariel Leader can, remember, be stripped with the engine in situ (using the correct puller to split the flywheel halves), so don't be too daunted by the prospect of a rebuild (as long as the asking price is right.

Check exhaust baffles for heavy coking. These can be cleaned or replaced, and complete silencers are available—albeit a little pricey. But running on a modern 35:1 oil/petrol mix (as opposed to the original 25:1) will significantly cut maintenance.



Riding the Ariel Leader

They're surprisingly good fun. That's the bottom line. Of course, a lot of that fun depends upon how much your head's been turned by the styling, because you certainly can't escape that. There's no other British bike that's quite like a Leader.

The weight distribution and balance is fairly good, even when riding two up. But the brakes are struggling at pretty much any speed.

Owners occasionally fit other brakes from other bikes, particularly at the front, but the loss of originality will hit you hard in the pocket. Only top Leaders sell for top money, and the braking is manageable once you adjust to it.

Otherwise, the controls are light and easy. Steering is light and steady. The suspension is adequate to good.

The weather protection is the unique selling point if you're planning to use a Leader as a daily ride, and because it has so much presence on the road, motorists tend to be a little more generous about sharing space. But take care, because there are still plenty of rubberneckers out there anxious to get a closer look.

The performance is acceptable, by modern standards. But you'll notice a real difference when carrying a passenger. There simply isn't much in reserve. So factor that in.

Cruising at 50-55mph is realistic and comfortable. Acceleration is fairly sprightly—unless you're used to modern two-strokes. But it's still a viable classic, and one that you really could comfortably tour upon.

Prices fluctuate significantly as these bikes slip into and out of fashion. Which is appropriate really because the world always was ambivalent about these wonderful two-strokes.

From the outset, they were as right as they were wrong. They were always both stylish and gaudy anachronisms right off the drawing board owing much of their philosophy to the early days of motorcycling before the conventions had been established.

We like them plenty, not only as a bold statement of British
engineering eccentricity, and not only as a reminder of the post-war optimism that died a sour death some time around the 1970s, but also because they're as much quirksome as irksome and that they challenge biking conventions.

Ride with pride. Ariel Leaders are simply cool.



Ariel Leader- stylish and sophisticated

▲ Len Harvey; another satisfied Ariel Leader customer






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Ariel Leader handlebars and instruments


Ariel Leader instrument console

Well equipped? Or over-endowed? Either way
you'll have more than the scenery to look at when
you pilot a Leader.

Ariel Leader headlight, indicators and legshields


Ariel Leader Fairing 

Neat. Stylish. Functional. This bike was a brave
attempt to claw back customers in an age when the
car was becoming king.

Ariel Leader panniers and luggage rack


Ariel Leader Panniers and Luggage Rack

So the panniers aren't exactly capacious,
but they will will give you somewhere to store the waterproofs, not that you'll need them often with that screen and leg shields. Note the luggage rack.

Ariel Leader rear view showing taillight, indicator and bumper detail


Ariel Leader rear view

A bumper on a motorcycle? They'll be putting on indicators next.

Ariel Leader silencer and bumper


Space age silencers

These emit a soft two-stroke sizzle that's easy on the ears and make even four-stroke men smile.

Ariel Leader kickstarter, gear lever and side panel detail


Side Panels on Ariel Leader

Side panels make maintenance a little more of a
chore (especially as you need to remove the kickstarter and gear lever), but you don't need to do it often on this bike.

Ariel Leader advert


▲ "Fast summer touring in your holiday clothes". That was how Ariel promoted the all-weather 250cc Ariel Leader.

Ariel Leader advert. Same owner, same machine


▲ "Same owner - same machine". Another Ariel advert extolling the virtues of a commuter bike that was also a great leisure tourer.

Ariel Leader motorcycle advert


▲ Ariel Arrow Super Sports ("Golden Arrow"), Leader and Arrow. Modern bikes for the post-war

jet-set. Val Page's Leader is every bit as classy as Alec Issigonis's Mini or Leo Fender's Stratocaster.

Ariel Leader brochure


▲ 1965 Ariel brochure.

* Thanks to Alan Donovan and Terry Stokes
for help with this feature.






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